1. DNA, Proteins and Protein Synthesis
It’s what cells do!

2. Biochemical Composition of Living Things
Nucleic acids are the instructions for making proteins, proteins make up traits
Nucleic Acids - store genetic information
• universal code (blueprints) for making proteins
Proteins - determine physical traits
• structure - materials for building cells
• function -
carry substances throughout the body, in & out of cells
trigger muscle movements
assist with all chemical reactions in the body
protect the body against disease
Other important molecules – carbohydrates and lipids (fats)

3. Nucleic Acids Building Blocks of Nucleic Acids Nucleotides
3 basic parts:   
Nucleotides make Nucleic Acids
• a phosphate group of one nucleotide attaches to the sugar of another nucleotide
• base pairing - bases bond with complimentary bases

4. Nucleic Acids Nucleotides  Purines - 2 carbon ring (big)
• guanine - 3 Hydrogen bonds
• adenine - 2 Hydrogen bonds
Pyrimidines - 1 carbon ring (small)
• cytosine - 3 Hydrogen bonds
• thymine - 2 Hydrogen bonds 

5. Nucleic Acids - DNA DNA - deoxyribonucleic acid contains genes
undergoes replication to produce new DNA strands
Replication occurs by complimentary base pairing
purine + purine = too big
pyrimidine + pyrimidine = too small
purine + pyrimidine = just right
A and T = two H bonds
C and G = three H bonds

6. Nucleic Acids - DNA DNA Replication
Produces an exact copy of the DNA molecule
complimentary base pairing from a template of DNA
Occurs before cell division - mitosis or meiosis

7. Nucleic Acids - DNA DNA Replication
Occurs simultaneously at many sites, called replication bubbles
Nucleotides always added from 3’ to 5’ end
Results in leading strand and lagging strand

8. Nucleic Acids - RNA RNA - ribonucleic acid
decodes genes within the DNA to make proteins
3 types: messenger, transfer, ribosomal
Nitrogenous bases = guanine, cytosine, adenine and uracil (not thymine)
complimentary base pairing is the same
 Cytosine-Guanine
 Adenine-Uracil

9. in nucleus, cytoplasm & ribosome
Comparing DNA & RNA
Sugars
Number of strands
Bases
Location
DNA
deoxyribose sugar
double-stranded
A-T
G-C
in the nucleus
RNA
ribose sugar
single-stranded
A-U
G-C
in nucleus, cytoplasm & ribosome
DNA
RNA

10. DNA  RNA  Protein  Trait
Protein Synthesis
DNA  RNA  Protein  Trait
Cells do their business by making proteins!

11. Protein Synthesis
DNA “blueprint” builds RNA in a process called Transcription.
RNA is then used to make proteins in a process called Translation.

12. Protein Synthesis - Transcription
DNA information copied onto mRNA with base-pairing rules Adenine + Uracil (not Thymine) Guanine + Cytoseine
mRNA molecule moves to cytoplasm, DNA stays in nucleus

13. Protein Synthesis - Translation
Nucleic acid language is ‘translated’ into protein language at the ribosome.
Glu
Met
Asp
mRNA codon is matched to tRNA anti-codon.
peptide bond
tRNA molecules attach to a specifc amino acid which is added to growing protein.

14. amino acid = methionine
Protein Synthesis - Translation
mRNA codon = AUG
tRNA anti-codon = UAC
amino acid = methionine

15. Protein Synthesis - Translation
tRNA molecules are ‘recycled’
Amino acids are attached with peptide bonds to form a polypeptide.

16. Protein Synthesis - Translation
This chart can be used to determine amino acid sequence from the mRNA codon.
Start in the center and work to the outside
Note that there are several mRNA codons for any one amino acid.

17. Protein Synthesis - Translation
Use the codon chart from the last slide to confirm the structure of this polypeptide.

18. Proteins Proteins = macromolecules Amino Acids = molecules
Amino Acids  Proteins
• proteins differ due to the number, kind, sequence and arrangement of amino acids
• amino acids are attached to one another by peptide bonds to form polypeptide chains

19. Proteins– Levels of Structure
Polypeptide chains arrange themselves into 3-dimensional structures to form functional proteins (they don’t work until this happens)
1º - a straight chain of amino acids
2º - chains bend and twist
3º - twisted chain folds even more; bonds form to hold the 3-dimensional shape
4º - Several polypeptide chains in the tertiary structure come together. This is a functional protein!

20. Proteins Examples - Protein Molecules
Structural - keratin (hair); collagen/elastin (skin); silk + web proteins in insects
Storage - ovalbumin (egg white); casein (milk)
Transport - hemoglobin (blood); cell membrane proteins
Regulation - hormones (insulin, estrogen) enzymes (lipase, DNA polymerase)
Receptors - neurotransmitter receptors (nerve cells) olfactory receptors (nose)
Contractile - actin + myosin (muscles)
Protection - antibodies